Context-aware wireless roaming

ABSTRACT

A wireless network infrastructure, comprising static and roaming mobile nodes (including one or more types of access-points), avoids unnecessary handoffs and unstable RF regions, and enables at least selected context-aware-capable mobile nodes to provide context-aware services to connected clients. More particularly, each of at least selected static nodes is enabled to provide the context-aware-capable mobile nodes with context information regarding the static node&#39;s relative position and direction, details of information served by the static node, special flags indicative of relevant impending changes in the foregoing parameters, and a range of signal strength values defining a stable RF zone for associated mobile nodes. Each context-aware-capable mobile node accordingly creates a context map that at least in part enables determination of the mobile node&#39;s next change in static node association and the preferred timing for the change.

CROSS REFERENCE TO RELATED APPLICATIONS

Priority/benefit claims for this application are made in theaccompanying Application Data Sheet. This application incorporates byreference for all purposes the following applications:

India Provisional Patent Application (Serial No. 3427/DEL/2012), filedNov. 6, 2012, first named inventor Sudhir HIRUDAYARAJ, and entitledCONTEXT-AWARE WIRELESS ROAMING.

PCT Application (Serial No. PCT/IB2013/059869), filed Nov. 3, 2013,first named inventor Sudhir HIRUDAYARAJ, and entitled CONTEXT-AWAREWIRELESS ROAMING.

U.S. Pat. No. 9,596,632 (Ser. No. 14/438,526), filed Apr. 24, 2015,first named inventor Sudhir HIRUDAYARAJ, and entitled CONTEXT-AWAREWIRELESS ROAMING.

BACKGROUND

Field

Advancements in wireless roaming in wireless mesh networks are needed toprovide improvements in cost, profitability, performance, efficiency,and utility of use.

Related Art

Unless expressly identified as being publicly or well known, mentionherein of techniques and concepts, including for context, definitions,or comparison purposes, should not be construed as an admission thatsuch techniques and concepts are previously publicly known or otherwisepart of the prior art. All references cited herein (if any), includingpatents, patent applications, and publications, are hereby incorporatedby reference in their entireties, whether specifically incorporated ornot, for all purposes.

A generic wireless infrastructure to support roaming of mobile units,each of which is responsible for switching traffic between clientsconnected to the mobile units and those connected to the fixed backbonenetwork, generally is subjected to one or more of the followingproblems:

-   -   1. Unpredictable handoff patterns: mobile units can roam from        any access-point (AP) to another, purely based on instantaneous        signal strength values, resulting in unpredictable changes in RF        conditions which leads to unpredictable changes in data rates.    -   2. Unnecessary handoffs: Each handoff from one access-point to        another carries with it a penalty both in terms of additional        computation because of tearing down and establishment of links        and in re routing of traffic through the new access-point and        any accompanying losses. A traditional wireless infrastructure        does nothing to minimize these handoffs.    -   3. Ping pong effect: A phenomenon related to the above mentioned        problem of unnecessary handoffs often occurs when a mobile unit        decides to roam to a particular access-point purely based upon        the signal strength seen from it, only to find itself roaming        back to its previous attachment in a very short span of time,        due to bad or unstable RF conditions. This typically happens        when the mobile unit decides to roam either too early or too        late to the next access-point.    -   4. Attachment in unstable RF zones: overlapping odd numbered        Fresnel zones and other RF phenomena can result in unstable RF        zones wherein, even when the signal strengths are very high,        data traffic may suffer from packet losses and fluctuations in        throughput. For example, the region immediately around the        antenna of any wireless unit is an unstable region with        unpredictable RF characteristics, which are bound to change        drastically as soon as the mobile unit crosses the antenna. If a        mobile unit decides to roam to an access-point in such a region,        its traffic will automatically suffer.

Thus, improvements in wireless infrastructure to better support theroaming of mobile units, and minimize or avoid the above problems, aredesired.

SYNOPSIS

The invention may be implemented in numerous ways, e.g., as a process,an article of manufacture, an apparatus, a system, a composition ofmatter, and a computer readable medium such as a computer readablestorage medium (e.g., media in an optical and/or magnetic mass storagedevice such as a disk, or an integrated circuit having non-volatilestorage such as flash storage), or a computer network wherein programinstructions are sent over optical or electronic communication links.The Detailed Description provides an exposition of one or moreembodiments of the invention that enable improvements in cost,profitability, performance, efficiency, and utility of use in the fieldidentified above. The Detailed Description includes an Introduction tofacilitate understanding of the remainder of the Detailed Description.The Introduction includes Example Embodiments of one or more of systems,methods, articles of manufacture, and computer readable media inaccordance with concepts described herein. As is discussed in moredetail in the Conclusions, the invention encompasses all possiblemodifications and variations within the scope of the issued claims.

A wireless network infrastructure, comprising static and roaming mobilenodes (including one or more types of access-points), avoids unnecessaryhandoffs and unstable RF regions, and enables at least selectedcontext-aware-capable mobile nodes to provide context-aware services toconnected clients. More particularly, each of at least selected staticnodes is enabled to provide mobile nodes capable of context-awarenesswith context information regarding the static node's relative positionand direction, details of information served by the static node, specialflags indicative of relevant impending changes in the foregoingparameters (for example, an upcoming change in direction, such asoccurring at an end-of-line terminal), and a range of signal strengthvalues defining a stable RF zone for associated mobile nodes. Eachcontext-aware-capable mobile node accordingly creates a context map thatat least in part enables determination of the mobile node's next changein static node association and the preferred timing for the change.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1a and 1b are plan views of illustrative predetermined pathembodiments, respectively for roadways and railways.

FIG. 2 is a flow chart of an illustrative predetermined path embodimentfrom the perspective of a mobile node.

FIG. 3 illustrates selected details of hardware aspects of an embodimentof an access-point (AP).

FIG. 4 illustrates selected details of software aspects of an embodimentof an access-point.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the invention isprovided below along with accompanying figures illustrating selecteddetails of the invention. The invention is described in connection withthe embodiments. The embodiments herein are understood to be merelyexemplary, the invention is expressly not limited to or by any or all ofthe embodiments herein, and the invention encompasses numerousalternatives, modifications, and equivalents. To avoid monotony in theexposition, a variety of word labels (including but not limited to:first, last, certain, various, further, other, particular, select, some,and notable) may be applied to separate sets of embodiments; as usedherein such labels are expressly not meant to convey quality, or anyform of preference or prejudice, but merely to conveniently distinguishamong the separate sets. The order of some operations of disclosedprocesses is alterable within the scope of the invention. Wherevermultiple embodiments serve to describe variations in process, method,and/or program instruction features, other embodiments are contemplatedthat in accordance with a predetermined or a dynamically determinedcriterion perform static and/or dynamic selection of one of a pluralityof modes of operation corresponding respectively to a plurality of themultiple embodiments. Numerous specific details are set forth in thefollowing description to provide a thorough understanding of theinvention. The details are provided for the purpose of example and theinvention may be practiced according to the claims without some or allof the details. For the purpose of clarity, technical material that isknown in the technical fields related to the invention has not beendescribed in detail so that the invention is not unnecessarily obscured.

INTRODUCTION

This introduction is included only to facilitate the more rapidunderstanding of the Detailed Description; the invention is not limitedto the concepts presented in the introduction (including explicitexamples, if any), as the paragraphs of any introduction are necessarilyan abridged view of the entire subject and are not meant to be anexhaustive or restrictive description. For example, the introductionthat follows provides overview information limited by space andorganization to only certain embodiments. There are many otherembodiments, including those to which claims will ultimately be drawn,discussed throughout the balance of the specification.

A wireless network infrastructure, comprising static and roaming mobilenodes (including one or more types of access-points, a.k.a. AP), avoidsunnecessary handoffs and unstable RF regions, and enables at leastselected context-aware-capable mobile nodes (a.k.a. mobile units) toprovide context-aware services to connected clients. More particularly,each of at least selected static nodes (a.k.a. static units) is enabledto provide the context-aware-capable mobile nodes with contextinformation (a.k.a. “roaming meta data”) regarding the static node'slocation and heading (relative position and direction with respect tothe mobile node), details of information served by the static node,special flags (a.k.a. “markers”) providing advance indication ofrelevant impending changes in the foregoing parameters, and a range ofsignal strength values defining a stable RF zone for associated mobilenodes.

In some embodiments, the static node provided context informationfurther includes one or more resource utilization metrics of the staticnode (such as one or more of computing, memory, and network loading).According to various embodiments, the mobile node independently locallyestablishes additional context information, such as one or more of: aGPS determined location of the mobile node, an administrator configuredlocation of the mobile node within a conveyance (such as at a particularend of the conveyance, or at a distance-offset with respect to aparticular end), and an administrator configured preference for aparticular radio (with its respective antenna type, placement, andorientation) of a plurality of radios of the mobile node. According tovarious embodiments, the preference for a particular radio is one of astatic preference, or a dynamic preference in accordance with apredetermined criteria (such as a function of the direction in which theconveyance is determined to be traveling).

The context information, however established, enables the context-awaremobile node to make the best possible decision regarding its nextaccess-point handoff, to eliminate bad handoffs, and also to providelocation and/or direction aware services to clients connected to thecontext-aware mobile node. The static node provided location and headingcontext information enable the context-aware mobile node to be locationaware, to continue to make optimum handoff decisions, and to continue toprovide location/direction services, even in regions where GPS serviceis not available and/or unreliable (such as tunnels and in undergroundrail links, where wireless-enabled), and in embodiments without GPS. Thestatic node provided resource utilization context information enablesthe context-aware mobile node to prefer attachment to a static node thatis not overloaded, other factors being equal.

Based on the information obtained from the static nodes in its vicinity,their signal strengths, and its own history of previous associations,each context-aware-capable mobile node creates a context map with itsrelative position, direction of motion, and any impending changes thatmight affect its operation and updates this map periodically. Thecontext map at least in part enables determination of the context-awaremobile node's next change in static node association and the preferredtiming for same. The context map enables the mobile node to optimallyassociate with the minimum possible number of static units for a givenpath of movement. This is desirable to minimize handoffs and the lossesarising therein, avoid the Ping-Pong effect (described in the backgroundsection), and provide access to information via the static units in asequential, ordered manner, such as video streams from cameras placedalong a road or railway track.

The embodiments herein are generally described wherein the static nodes(a.k.a. static units) are referred to as “access-points”, while themobile nodes (a.k.a. mobile units) are not explicitly described asaccess-points. Nevertheless, it will be understood that according tovarious embodiments, one or more client nodes traveling with each mobilenode communicate with the mobile node in an ad hoc mode (peer-to-peer),or in infrastructure mode (with the mobile node acting as anaccess-point at least with respect to the client nodes). The mobilenodes that are enabled to be context-aware are referred to ascontext-aware mobile nodes. In various embodiments it is preferred, butnot required, that all of the mobile nodes in a mesh network arecontext-aware mobile nodes. It is also understood, that from theperspective of the static access-points, the mobile nodes may be viewedas clients.

According to various embodiments, at least some of the static nodes actas a gateway to one or more of a fixed backbone, intranet, wide areanetwork, and the Internet. Further according to various embodiments, atleast some of the static nodes provide associated mobile nodes withaccess to respective information streams, such as a respective videocamera connected to the static node.

EXAMPLE EMBODIMENTS

In concluding the introduction to the detailed description, what followsis a collection of example embodiments, including at least someexplicitly enumerated as “ECs” (Example Combinations), providingadditional description of a variety of embodiment types in accordancewith the concepts described herein; these examples are not meant to bemutually exclusive, exhaustive, or restrictive; and the invention is notlimited to these example embodiments but rather encompasses all possiblemodifications and variations within the scope of the issued claims andtheir equivalents.

EC1) A wireless mobile node, comprising:

-   -   means for automatically capturing and interpreting roaming        meta-data advertised by one or more static access-points in the        vicinity of the mobile node;    -   means for automatically reconfiguring the mobile node,        contingently based on predetermined criteria, to associate with        a next access-point of an ordered list communicated via the        roaming meta-data; and    -   wherein the mobile node and the static access-points are        respective nodes of a wireless mesh network.

EC2) The wireless mobile node of EC1, further comprising:

-   -   means for automatically evaluating whether the signal strength        observed for a currently associated access-point is within a        predetermined signal strength range communicated via the roaming        meta-data; and    -   wherein the predetermined criteria for the reconfiguring is a        function of at least that the observed signal strength exceeds        the predetermined signal strength range.

EC3) The wireless mobile node of EC1, further comprising:

-   -   means for automatically determining whether the mobile node has        encountered a marker communicated via the roaming meta-data; and    -   wherein the predetermined criteria for the reconfiguring is a        function of at least the marker encounter determination.

EC4) The wireless mobile node of EC1, further comprising:

-   -   means for automatically determining a Fresnel zone status; and    -   wherein the predetermined criteria for the reconfiguring is a        function of at least the Fresnel zone status.

EC5) The wireless mobile node of EC1, further comprising:

-   -   means for automatically determining location and direction of        movement based on the roaming meta-data.

EC6) A wireless mobile node of EC1, wherein the roaming meta-data isembedded in one or more Information Elements (IEs) of beacon frames ofthe static access-point.

EC7) The wireless mobile node of EC1, wherein the mobile node iscompatible with at least one revision of the IEEE 802.11 standard.

EC8) The wireless mobile node of EC2 wherein the mobile node is enabledfor travel via a conveyance that nominally travels a predetermined pathalong a transportation corridor.

EC9) The wireless mobile node of EC8 wherein the mobile node is a mobileaccess-point enabled to provide context-based services to mobile clientsassociated with the mobile node.

EC10) The wireless mobile node of EC9 wherein the context-based servicesinclude video streamed from the static access-point currently associatedwith the mobile node.

EC11) The wireless mobile node of EC9 wherein the mobile nodes and anymobile clients are provided connectivity to a fixed backbone via theassociated static access-point.

EC12) The wireless mobile node of EC8 wherein overall data throughputobserved by the mobile node is increased by minimizing packet lossesattributable to unstable RF regions and eliminating unnecessary handoffsto non-optimal access-points.

EC13) The wireless mobile node of EC8 wherein the predetermined criteriafor the reconfiguring comprises a context map created and periodicallyupdated by the mobile node based on the current signal strength, historyof past associations, and advertised roaming meta-data, of staticaccess-points in the vicinity of the mobile node.

EC14) The wireless mobile node of EC13 wherein the context map isfurther used to determine the timing at which the mobile nodedisassociates with a given static access-point of the staticaccess-points.

EC15) The wireless mobile node of EC13 wherein the the context map isfurther used to determine the timing at which the mobile node is enabledto associate with a given static access-point of the staticaccess-points.

EC16) A wireless mesh network, comprising:

-   -   means for identifying an ordering of static node access-points        of the wireless mesh network;    -   means for delivering the ordering to mobile nodes of the        wireless mesh network;    -   means for determining the best next static node access-point, of        the static node access-points, for each mobile node to roam to;        and    -   wherein handoffs of the mobile nodes between the static node        access-points contrary to the ordering are eliminated.

EC17) A computer readable medium having a set of instructions storedtherein that when executed by a processing element cause the processingelement to perform operations comprising:

-   -   automatically capturing and interpreting roaming meta-data        advertised by one or more wireless static access-points in the        vicinity of a wireless mobile node;    -   automatically reconfiguring the wireless mobile node,        contingently based on predetermined criteria, to associate with        a best next wireless static access-point of the wireless static        access-points based on an ordered list communicated via the        roaming meta-data;    -   automatically evaluating whether the signal strength observed        for a currently associated wireless static access-point is        within a predetermined signal strength range communicated via        the roaming meta-data;    -   automatically determining the timing at which the wireless        mobile node is enabled to associate with, and is required to        disassociate from, a given wireless static access-point of the        wireless static access-points;    -   automatically determining whether the wireless mobile node has        encountered a marker communicated via the roaming meta-data;    -   automatically determining location and direction of movement of        the wireless mobile node based on the roaming meta-data; and    -   wherein the wireless mobile node and the wireless static        access-points are respective nodes of a wireless mesh network.

EC18) A method comprising:

-   -   automatically capturing and interpreting roaming meta-data        advertised by one or more wireless static access-points in the        vicinity of a wireless mobile node; and    -   automatically reconfiguring the wireless mobile node, in        response to predetermined criteria and based on an ordered list        communicated via the roaming meta-data, to associate with a best        next wireless static access-point of the wireless static        access-points; and    -   wherein the wireless mobile node and the wireless static        access-points are respective nodes of a wireless mesh network.

EC19) The method of EC18, further comprising:

-   -   automatically evaluating whether the signal strength observed        for a currently associated access-point is within a        predetermined signal strength range communicated via the roaming        meta-data; and    -   wherein the predetermined criteria for the reconfiguring is a        function of at least that the observed signal strength exceeds        the predetermined signal strength range.

EC20) The method of EC18, further comprising:

-   -   automatically determining whether the mobile node has        encountered a marker communicated via the roaming meta-data; and    -   wherein the predetermined criteria for the reconfiguring is a        function of at least the marker encounter determination.

EC21) The method of EC18, wherein the predetermined criteria for thereconfiguring comprises a context map created and periodically updatedby the mobile node based on the current signal strength, history of pastassociations, and advertised roaming meta-data, of static access-pointsin the vicinity of the mobile node.

EC22) The method of EC21, wherein the context map is further used todetermine the timing at which the mobile node disassociates with a givenstatic access-point of the static access-points.

EC23) The method of EC21, wherein the context map is further used todetermine the timing at which the mobile node is enabled to associatewith a given static access-point of the static access-points.

EC24) The method of EC18, further comprising:

-   -   automatically determining a Fresnel zone status; and    -   wherein the predetermined criteria for the reconfiguring is a        function of at least the Fresnel zone status and overall data        throughput observed by the mobile node is increased by        minimizing packet losses attributable to unstable RF regions and        eliminating unnecessary handoffs to non-optimal access-points.

EC25) The method of EC18, further comprising:

-   -   automatically determining location and direction of movement        based on the roaming meta-data; and    -   wherein the mobile node is a mobile access-point enabled to        provide context-based services to mobile clients associated with        the mobile node.

EC26) The method of EC25, wherein the mobile node is enabled to performthe reconfiguring and provide the context-based services inwireless-enabled regions without requiring a clear view of the sky.

EC27) The method of EC21, wherein the context map further includescontext information established by the mobile node independently fromcontext information provided by the static access-points.

EC28) The method of EC27, wherein the context information established bythe mobile node comprises one or more of a GPS determined location ofthe mobile node, an administrator configured location of the mobile nodewithin a conveyance, an administrator configured preference for aparticular radio of a plurality of radios of the mobile node, and acomputed result of a predetermined function.

EC29) The method of EC21, wherein the static access-point advertisedroaming-data comprises one or more of: the static node's relativeposition and direction with respect to the mobile node, details ofinformation served by the static node, advance indication of impendingchanges, a range of signal strength values defining a stable RF zonewith respect to the mobile node, and at least one resource utilizationmetric of the static node.

EC30) The method of EC18, wherein the roaming meta-data is embedded inone or more 802.11 management frames of the static access-point.

MOBILE WIRELESS ROAMING OPTIMAL ASSOCIATIONS

Various embodiments provide for the configuration of a signal strengthrange on a per static node access-point basis, so as to enable eachcontext-aware mobile node to optimally decide when to associate andlater disassociate with an access-point. This is done using a pair ofsignal strength values <Rmin, Rmax>. Rmin specifies a minimum signalstrength threshold value to enable association with the access-point.For signal strength below Rmin, the mobile unit will not associate withthe access-point. Rmax specifies a maximum signal strength thresholdvalue beyond which association with the access-point is undesirable. Forsignal strength above Rmax (and associated with short paths), it isdesirable for the mobile unit to automatically disassociate from theaccess-point corresponding to the signal above Rmax and associate withthe best next access-point, even though the best next access-point has alower signal strength than the current access-point (and is likelyfarther away than the current access-point).

In at least some context-aware embodiments, signal strengths correspondto a Received Signal Strength Indicator (RSSI), and an RSSI above Rmax(a.k.a. “RSSI-bad”) is associated with “bad Fresnel zones” (or simply“bad zones”). The location of the bad zones (associated with destructiveinterference due to reflections), in terms of RSSI-bad demarcatedregions, is generally different for every access-point. While the badFresnel zones are to a degree predictable based on the heights of anddistances between the antennas of the static and mobile nodes, in atleast some embodiments the bad zones are empirically determined viafield testing (a.k.a. calibration, mapping, or training) of the mobilenodes.

MOBILE WIRELESS ROAMING ALONG PRE-DETERMINED PATHS

The context-aware roaming techniques taught herein are particularlybeneficial in wireless network embodiments where mobile nodes (such asheavy-rail, light-rail, and rapid-transit trains, monorails, maglevs,metros, subways, elevateds, interurbans, trams, people movers, otherairport transit, and buses) roam along repeatedly using pre-determinedpaths, particularly such as found in metropolitan transit deployments.In embodiments involving such pre-determined paths, the infrastructureenables an ordering of the static node access-points and communicatingthe ordering to the mobile nodes. The mobile nodes are then enabled touse the ordering to determine the best next access-point to roam to andthereby eliminate any unnecessary handoffs (such as ping-ponging) thatare not in accordance with the ordering.

In at least some pre-determined path embodiments, there is a singledirection looped path, or parallel oppositely directed paths (forexample, “outbound” and “inbound”), with a respective set of orderedaccess-points per path direction. In these embodiments, each mobile nodeis programmed to only associate with the ordered access-pointscorresponding to the direction in which the node is traveling (or willbe traveling subsequent to a direction reversal indicated by a marker).This enables the use of conventional static node access-pointsprovisioned by administrative management software to broadcast staticroaming meta-data.

In a first type of pre-determined path embodiment, the ordering isconveyed via access-point sequence numbers (for example, AP1, AP2, AP3 .. . AP4) included in the roaming meta-data. In a second type ofpre-determined path embodiment (not necessarily exclusive of the firsttype), the ordering is learned by the context-aware mobile nodes, suchas via test runs (a.k.a. calibration, mapping, or training runs) overthe pre-determined path.

ROAMING META-DATA IMPLEMENTATION

By way of example only, in at least some 802.11 embodiments, the roamingmeta-data is broadcast (advertised) via data embedded in InformationElements (IEs) of 802.11 beacon frames. That is, the 802.11 beacon frameIEs are employed to make roaming more efficient. Context-aware mobilenodes will be enabled to absorb the roaming meta-data from the IEs,while conventional mobile clients will simply ignore it. According tovarious embodiments, the roaming meta-data (context information) ispropagated using one or more of a) IEs of 802.11 beacon frames, and b)one or more other 802.11 management frames, such as one or more of proberequests and responses.

Making use of conventional hardware and software for the static nodeaccess-points, administrative management software is used to program theaccess-points to emit the desired roaming meta-data (for example, viathe 802.11 beacon frame IEs), which in at least some embodiments isstatic roaming meta-data, albeit specific (custom configured) to eachaccess-point. That is, the relative position and direction (of thestatic node with respect to the mobile node), bad zone information,markers, and any other roaming meta-data programmed for broadcast, arerespective to each access-point.

Making use of otherwise conventional hardware, the context aware mobilenodes are augmented (such as via a firmware upgrade) to addfunctionality to capture and decode the roaming meta-data from thestatic nodes, evaluate in real time various pre-determined decisiontrees in view of the roaming meta-data and other parametric data (suchas RSSI), and dynamically alter their access-point associationsaccordingly.

PREDETERMINED PATH BASED ROAMING EXAMPLES

FIG. 1a and FIG. 1b are plan views of illustrative directed pathembodiments, respectively for roadway and railway based mobile nodes.Certain features may be more readily discerned in FIG. 1 a, due to lessvisual clutter, but other than specific differences called out, theembodiments are otherwise identical. In FIG. 1 a, small segments of tworoadways, Roadway RDW1 121 and Roadway RDW2 122, are shown at the top ofthe drawing. At the top of FIG. 1 b, small segments of two railways areshown: Railway RLW1 123 and Railway RLW2 124. The ellipsis in the uppercenter of each of these drawings is intended to convey that there is asubstantive separation distance between the left and rightroadway/railway segments. The description that follows directlydescribes the embodiment of FIG. 1 a. Substituting “railways”,“Railway”, RLW1, RLW2, MN5, MN6, MN7, and MN8, respectively for“roadways”, “Roadway”, RDW1, RDW2, MN1, MN2, MN3, and MN4, provides arespective description of the embodiment of FIG. 1 b. Each mobile nodeis installed at a chosen location within each conveyance (such as at oneof the two ends of a train, or at a distance-offset from one of theends, determined in view of convenience and engineering economics). Insome embodiments, there are multiple mobile nodes within a sameconveyance (such as a mobile node located at each end of a train).

As detailed below, mobile nodes MN1, MN2, MN3, and MN4 are traveling onthe roadways, and Static Nodes SN1, SN2, SN3, and SN4 are adjacent tothe roadways. By way of example, SN1 is statically associated with SN4(via link 150-10), as is SN2 statically associated with SN3 (via link150-11). SN3 and SN4 are further associated (with the various linksillustrated), respectively with SN6 and SN5, with Network 160,additionally comprising SN7, SN8, SN9, and SN10. SN8 is furtherdesignated a central server, used in some embodiments for centralizedmanagement and/or storage (such as functions and databases formonitoring, provisioning, authentication, operations logging, andbackup) of at least some of the static and mobile nodes. Network 160 isany of a backbone or portion thereof, an intranet, a wide area network,or other network infrastructure supporting a directed pathimplementation of context-aware roaming. In some embodiments, network160 is coupled to, or a part of, the Internet 170. The associationsgiven are merely exemplary, and other associations are possible.

At the time corresponding to the illustration, Mobile Nodes MN1 111 andMN2 112 are traveling right-to-left on Roadway RDW1 121. Static NodesSN1 101 and SN2 102 advertise that they service right-to-left traffic inan ordered sequence (of SN2 followed by SN1), and have respective BadFresnel Zones BFZ1 141 and BFZ2 142. Concurrently at the time of theillustration, Mobile Nodes MN3 113 and MN4 114, are travelingleft-to-right on Roadway RDW2 122. Static Nodes SN3 103 and SN4 104advertise that they service left-to-right traffic in an ordered sequence(SN4 followed by SN3), and have respective Bad Fresnel Zones BFZ3 143and BFZ4 144. The bad Fresnel zones are demarcated by Rmax valuesrespective to and advertised by each static node.

While traveling right-to-left, MN1 and MN2 are programmed to associateonly with SN2 and SN1 and in accordance with the sequence numberingadvertised by these static nodes. At the time corresponding to theillustration, MN2 is associated with SN2, but will change association toSN1 upon entering into BFZ2, which will be inferred via a detected RSSIvalue corresponding to the Rmax value advertised for BFZ2. Similarly,while traveling left-to-right, MN3 and MN4 are programmed to associateonly with SN3 and SN4 and in accordance with the sequence numberingadvertised by these static nodes. At the time of the illustration, MN3is associated with SN4, but will change association to SN3 upon enteringBFZ4, which will be inferred via a detected RSSI value corresponding tothe Rmax value advertised for BFZ4.

Each of the static nodes SN1, SN2, SN3, and SN4 is shown optionallycoupled respectively to at least video cameras VC1 181, VC2 182, VC3183, and VC4 184. According to various embodiments, the video camerasprovide at least the operators and/or passengers of the mobile nodesassociated with the corresponding static nodes, with selected videostreams (such as of a transit stop, platform, or surrounding area),providing advance awareness that can promote one or more of safety,security, and efficiency (for example, via showing pedestriandensity/traffic flows).

FIG. 2 is a flow chart of an illustrative predetermined path embodimentfrom the perspective of a mobile node. The mobile node (such as any ofMN1, MN2, MN3, or MN4, of FIG. 1a or 1 b) is initialized in action 210.In action 220, a new ordered sequence of access-points (AP)corresponding to a particular directed path is adopted, and a particularaccess-point in the ordered sequence is selected and associated with bythe mobile node. In action 230, the roaming meta-data being advertisedby the currently associated access-point is captured, decoded, andexecuted (carried out or put in place, as required, where applicable).

Association with the current access-point continues consistent with aperiodic assessment of status. In particular, a periodic evaluation ismade regarding whether the mobile node has entered a bad Fresnel zone orif a marker (advertised in the roaming meta-data) is detected thatsignifies a path change (such as a turn-around at an end terminal of theline). The evaluation for a bad Fresnel zone (exemplified by RSSIexceeding Rmax), is represented by decision 240. If the mobile node isin a bad Fresnel zone, in action 245, the mobile node changesassociation to the next access-point in the current ordered sequence.Assuming the mobile node is not in a bad Fresnel zone, the checking fora path change marker is represented by decision 250. Upon notificationof the path change (by confirmation of a respective marker), controlflow loops back to carry out action 220 (discussed above). If neither abad Fresnel zone nor a path change is detected, association with thecurrent access-point continues unchanged, with control flow looping backto carry out action 230 (also as previously discussed).

AP HARDWARE

FIG. 3 illustrates selected details of hardware aspects of an embodimentof an AP, such as any of static or mobile nodes of FIG. 1a or 1 b. Theillustrated AP includes Processor 305 coupled to various types ofstorage, including volatile read/write memory “Memory Bank” elements301.1-2 via DRAM Memory Interface 302, and non-volatile read/writememory Flash 303 and EEPROM 304 elements. According to variousembodiments, the processor is further coupled to Ethernet Interface 306providing a plurality of Ethernet Ports 307 for establishing wiredlinks, and Wireless Interfaces 309-9 and 309-N providing radiocommunication of packets for establishing wireless links. The wiredlinks provide communication between the illustrated AP and, for example,other APs or a centralized resource. The wireless links providecommunication between the illustrated AP and, for example, another APand/or a client of the illustrated AP. In some embodiments, some of theWireless Interfaces are compatible with an IEEE 802.11 wirelesscommunication standard (such as any of 802.11a, 802.11b, 802.11g, and802.11n). In some embodiments, GPS subsystem 310 provides an additionalsource of location context information. In some embodiments, one or moreof the nodes have a plurality of radios with respective antennas of oneor more of: a) different type, b) different placement, and c) differentadministrator configured orientation. By way of example only, in someembodiments, different antennas of the same mobile node areadministrator configured to face in opposite directions. The illustratedpartitioning is only one example, as other equivalent embodiments of anAP are possible.

In operation, the processor fetches instructions from any combination ofthe storage elements (such as DRAM, Flash, and EEPROM) that operate ascomputer readable media, and executes the instructions. Some of theinstructions correspond to software associated with operating the mobilenodes to capture, decode, and execute advertised roaming meta-data forcontext-aware wireless roaming. Some of the instructions correspond tosoftware associated with operating the mobile nodes in accordance withoptimal access-point selection in view of bad Fresnel zones. In variousembodiments, some of the instructions correspond to software associatedwith predetermined-path-based roaming. In some embodiments, some of theinstructions correspond to all or any portion of software illustrated inFIG. 4, such as NMS Manager 401, Ethernet Driver 414, and Radio Driver415.

AP SOFTWARE

FIG. 4 illustrates selected details of software aspects of an embodimentof an AP, such as any of static or mobile nodes of Figs. la or lb, asfurther qualified below. Various software modules are illustrated in acontext that conceptually illustrates AP communication and connectivitycapability as Hardware Interfaces 420. The illustrated software includesNetwork Management System Manager (NMS Manager, a.k.a. NMS) 401interfacing to Network Interface Manager 402 and Fault, Configuration,Accounting, Performance, and Security Manager (FCAPS Manager, a.k.a.FCAPS) 403. In some embodiments, the NMS Manager interfaces betweenmanagement software operating external to the AP and software operatinginternal to the AP (such as various applications and FCAPS). The NetworkInterface Manager manages physical network interfaces, such as theEthernet and Wireless Interfaces of an AP, as illustrated by EthernetInterface 306 (also illustrated in FIG. 3) and Wireless Interfaces 309(representative of Wireless Interfaces 309-A . . . 309-N of FIG. 3). TheNetwork Interface Manager assists the NMS in passing dynamicconfiguration changes (as requested by a user) through the managementsoftware to FCAPS. In some embodiments, FCAPS includes functions tostore and retrieve configuration information, and FCAPS functions serveall applications requiring persistent configuration information. FCAPSoptionally assists in collecting fault information and statistics andperformance data from various operating modules of the AP. FCAPSselectively passes any portion or all of the collected information,statistics, and data to the NMS.

Kernel Interface 410 interfaces the Managers to AP Core Functions 411and Flash File System module 413. AP Core Functions 411 includes Routingand Transport Protocols layer 411 a, implemented by both static andmobile nodes, and Context-Aware Functions 411 b, implemented at least bycontext-aware mobile nodes. The Transport Protocols include TCP and UDP.In some embodiments, the minimum static node AP core functionalityrequires no changes from the Routing and Transport Protocols layer 411 afound in a conventional AP, the context-aware meta-data beingprogrammable for advertisement (as discussed elsewhere herein) viaconventional administrative management software. In some embodiments,the mobile node AP core functionality is implementable via firmwareupgrade of a conventional AP to add the Context-Aware Functions 411 b.The Context-Aware Functions 411 b, comprise capture, decode, and use ofthe roaming meta-data advertised by selected static nodes. According tovarious embodiments, the mobile node independently locally establishesadditional context information (roaming meta data), such as one or moreof: a GPS subsystem determined location of the mobile node, anadministrator configured location of the mobile node within aconveyance, and an administrator configured preference for a particularradio (with its respective antenna type, placement, and orientation) ofa plurality of radios of the mobile node. Exemplary uses of the roamingmeta-data by the mobile nodes (discussed along with other uses in moredetail elsewhere herein) include: roaming based on AP-specific <Rmin,Rmax> signal strength thresholds, roaming based on an ordered APsequence (for example, corresponding to a particular predeterminedpath), actions based on the recognition of markers (such as adopting adifferent ordered AP sequence at the end of a transit line), andproviding context-aware services (such as location-based services, e.g.video streamed from an upcoming transit stop).

The Flash File System module interfaces to Flash Driver 416 that isillustrated conceptually coupled to Non-Volatile hardware element 423that is representative of a flash file system (e.g. data organized in anon-volatile memory) stored in any combination of Flash 303 and EEPROM304 elements of FIG. 3. Layer-2 Abstraction Layer 412 interfaces theRouting and Transport Protocols to Ethernet and Radio Drivers 414 and415, respectively. The Ethernet Driver is illustrated conceptuallycoupled to Ethernet Interface 306 of FIG. 3. The Radio Driver isillustrated conceptually coupled to Wireless Interfaces 309 that isrepresentative of the Wireless Interfaces 309-A . . . 309-N of FIG. 3.In some embodiments, the software includes a serial driver. The softwareis stored on a computer readable medium (e.g. any combination of theDRAM, Flash, and EEPROM elements), and is executed by a programmableelement, such as Processor 305 of FIG. 3. The illustrated partitioningis an example only, as many other equivalent arrangements of layers arepossible.

In various embodiments, any combination of all or portions of softwarerelating to operating the AP to capture, decode, execute advertisedroaming meta-data for context-aware wireless roaming, operating themobile nodes in accordance with optimal access-point selection in viewof bad Fresnel zones, and/or carry out predetermined-path-based roaming,is included in any combination of NMS Manager 401, AP Core Functions411, Ethernet Driver 414, Radio Driver 415, and other software modulesnot explicitly illustrated in FIG. 4.

EXAMPLE IMPLEMENTATION TECHNIQUES

In some embodiments, various combinations of all or portions ofoperations performed by portions of a processor, microprocessor,system-on-a-chip, application-specific-integrated-circuit, hardwareaccelerator, or other circuitry providing all or portions of theaforementioned AP and context-aware operations, such as the control flowof FIG. 2 and the AP Core Functions 411 of FIG. 4, are specified by aspecification compatible with processing by a computer system. Thespecification is in accordance with various descriptions, such ashardware description languages, circuit descriptions, netlistdescriptions, mask descriptions, or layout descriptions. Exampledescriptions include: Verilog, VHDL, SPICE, SPICE variants such asPSpice, IBIS, LEF, DEF, GDS-II, OASIS, or other descriptions. In variousembodiments, the processing includes any combination of interpretation,compilation, simulation, and synthesis to produce, to verify, or tospecify logic and/or circuitry suitable for inclusion on one or moreintegrated circuits. Embodiments are thus contemplated wherein any oneor more of the context-aware features described elsewhere herein are atleast in part implemented in hardware. Each integrated circuit,according to various embodiments, is designable and/or manufacturableaccording to a variety of techniques. The techniques include aprogrammable technique (such as a field or mask programmable gate arrayintegrated circuit), a semi-custom technique (such as a wholly orpartially cell-based integrated circuit), and a full-custom technique(such as an integrated circuit that is substantially specialized), anycombination thereof, or any other technique compatible with designand/or manufacturing of integrated circuits.

In some embodiments, various combinations of all or portions ofoperations as described by a computer readable medium having a set ofinstructions stored therein, are performed by execution and/orinterpretation of one or more program instructions, by interpretationand/or compiling of one or more source and/or script languagestatements, or by execution of binary instructions produced bycompiling, translating, and/or interpreting information expressed inprogramming and/or scripting language statements. The statements arecompatible with any standard programming or scripting language (such asC, C++, Fortran, Pascal, Ada, Java, VBscript, and Shell). One or more ofthe program instructions, the language statements, or the binaryinstructions, are optionally stored on one or more computer readablestorage medium elements. In various embodiments, some, all, or variousportions of the program instructions are realized as one or morefunctions, routines, sub-routines, in-line routines, procedures, macros,or portions thereof.

CONCLUSION

Certain choices have been made in the description merely for conveniencein preparing the text and drawings, and unless there is an indication tothe contrary, the choices should not be construed per se as conveyingadditional information regarding structure or operation of theembodiments described. Examples of the choices include: the particularorganization or assignment of the designations used for the figurenumbering and the particular organization or assignment of the elementidentifiers (the callouts or numerical designators, e.g.) used toidentify and reference the features and elements of the embodiments.

The words “includes” or “including” are specifically intended to beconstrued as abstractions describing logical sets of open-ended scopeand are not meant to convey physical containment unless explicitlyfollowed by the word “within.”

Although the foregoing embodiments have been described in some detailfor purposes of clarity of description and understanding, the inventionis not limited to the details provided. There are many embodiments ofthe invention. The disclosed embodiments are exemplary and notrestrictive.

It will be understood that many variations in construction, arrangement,and use are possible consistent with the description, and are within thescope of the claims of the issued patent. For example, interconnect andfunction-unit bit-widths, clock speeds, and the type of technology usedare variable according to various embodiments in each component block.The names given to interconnect and logic are merely exemplary, andshould not be construed as limiting the concepts described. The orderand arrangement of flowchart and flow diagram process, action, andfunction elements are variable according to various embodiments. Also,unless specifically stated to the contrary, value ranges specified,maximum and minimum values used, or other particular specifications, aremerely those of the described embodiments, are expected to trackimprovements and changes in implementation technology, and should not beconstrued as limitations.

Functionally equivalent techniques known in the art are employableinstead of those described to implement various components, sub-systems,operations, functions, routines, sub-routines, in-line routines,procedures, macros, or portions thereof. It is also understood that manyfunctional aspects of embodiments are realizable selectively in eitherhardware (e.g., generally dedicated circuitry) or software (e.g., viasome manner of programmed controller or processor), as a function ofembodiment dependent design constraints and technology trends of fasterprocessing (facilitating migration of functions previously in hardwareinto software) and higher integration density (facilitating migration offunctions previously in software into hardware). Specific variations invarious embodiments include, but are not limited to: differences inpartitioning; different form factors and configurations; use ofdifferent operating systems and other system software; use of differentinterface standards, network protocols, or communication links; andother variations to be expected when implementing the concepts describedherein in accordance with the unique engineering and businessconstraints of a particular application.

The embodiments have been described with detail and environmentalcontext well beyond that required for a minimal implementation of manyaspects of the embodiments described. Those of ordinary skill in the artwill recognize that some embodiments omit disclosed components orfeatures without altering the basic cooperation among the remainingelements. It is thus understood that much of the details disclosed arenot required to implement various aspects of the embodiments described.To the extent that the remaining elements are distinguishable from theprior art, components and features that are omitted are not limiting onthe concepts described herein.

All such variations in design are insubstantial changes over theteachings conveyed by the described embodiments. It is also understoodthat the embodiments described herein have broad applicability to othercomputing and networking applications, and are not limited to theparticular application or industry of the described embodiments. Theinvention is thus to be construed as including all possiblemodifications and variations encompassed within the scope of the claimsof the issued patent.

What is claimed is:
 1. A method comprising: automatically capturing andinterpreting roaming meta-data advertised by one or more staticaccess-points in the vicinity of a wireless mobile node; automaticallyreconfiguring the wireless mobile node, in response to predeterminedcriteria and based on an ordered list communicated via the roamingmeta-data, to associate with a best next static access-point of thestatic access-points, the best next static access-point being a nextaccess-point in the ordered list; wherein the wireless mobile node andthe static access-points are respective nodes of a wireless meshnetwork; and wherein the predetermined criteria comprises a context mapcreated and periodically updated by the wireless mobile node based oncurrent signal strength, history of past associations, and advertisedroaming meta-data, of at least some of the static access-points.
 2. Themethod of claim 1, further comprising automatically determining locationand direction of movement based on the roaming meta-data.
 3. The methodof claim 1, wherein the wireless mobile node is a mobile access-pointenabled to provide context-based services to mobile clients associatedwith the wireless mobile node.
 4. The method of claim 1, furthercomprising: automatically determining whether the wireless mobile nodehas encountered a marker communicated via the roaming meta-data; andwherein the predetermined criteria is a function of at least the markerencounter determination.
 5. The method of claim 1, wherein the contextmap is further used to determine when the wireless mobile nodedisassociates with a given static access-point of the staticaccess-points.
 6. The method of claim 1, wherein the context map isfurther used to determine when the wireless mobile node is enabled toassociate with a given static access-point of the static access-points.7. The method of claim 1, further comprising: automatically evaluatingwhether signal strength observed for a currently associated one of thestatic access-points is within a predetermined signal strength rangecommunicated via the roaming meta-data; and wherein the predeterminedcriteria is a function of at least that the observed signal strengthexceeds the predetermined signal strength range.
 8. A non-transitorycomputer readable medium having a set of instructions stored thereinthat when executed by a processing element cause the processing elementto perform operations comprising: automatically capturing andinterpreting roaming meta-data advertised by one or more staticaccess-points in the vicinity of a wireless mobile node; automaticallyreconfiguring the wireless mobile node, in response to predeterminedcriteria and based on an ordered list communicated via the roamingmeta-data, to associate with a best next static access-point of thestatic access-points, the best next static access-point being a nextaccess-point in the ordered list; wherein the wireless mobile node andthe static access-points are respective nodes of a wireless meshnetwork; and wherein the predetermined criteria comprises a context mapcreated and periodically updated by the wireless mobile node based oncurrent signal strength, history of past associations, and advertisedroaming meta-data, of at least some of the static access-points.
 9. Thenon-transitory computer readable medium of claim 8, wherein theoperations further comprise automatically determining location anddirection of movement based on the roaming meta-data.
 10. Thenon-transitory computer readable medium of claim 8, wherein the wirelessmobile node is a mobile access-point enabled to provide context-basedservices to mobile clients associated with the wireless mobile node. 11.The non-transitory computer readable medium of claim 8, furthercomprising: wherein the operations further comprise automaticallydetermining whether the wireless mobile node has encountered a markercommunicated via the roaming meta-data; and wherein the predeterminedcriteria is a function of at least the marker encounter determination.12. The non-transitory computer readable medium of claim 8, wherein thecontext map is further used to determine when the wireless mobile nodedisassociates with a given static access-point of the staticaccess-points.
 13. The non-transitory computer readable medium of claim8, wherein the context map is further used to determine when thewireless mobile node is enabled to associate with a given staticaccess-point of the static access-points.
 14. The non-transitorycomputer readable medium of claim 8, further comprising: wherein theoperations further comprise automatically evaluating whether signalstrength observed for a currently associated one of the staticaccess-points is within a predetermined signal strength rangecommunicated via the roaming meta-data; and wherein the predeterminedcriteria is a function of at least that the observed signal strengthexceeds the predetermined signal strength range.
 15. A mobile node,comprising: means for automatically capturing and interpreting roamingmeta-data advertised by one or more static access-points in the vicinityof the mobile node; means for automatically reconfiguring the mobilenode, in response to predetermined criteria and based on an ordered listcommunicated via the roaming meta-data, to associate with a best nextstatic access-point of the static access-points, the best next staticaccess-point being a next access-point in the ordered list; wherein themobile node and the static access-points are respective nodes of awireless mesh network; and wherein the predetermined criteria comprisesa context map created and periodically updated by the mobile node basedon current signal strength, history of past associations, and advertisedroaming meta-data, of at least some of the static access-points.
 16. Themobile node of claim 15, further comprising means for automaticallydetermining location and direction of movement based on the roamingmeta-data.
 17. The mobile node of claim 15, wherein the mobile node is amobile access-point enabled to provide context-based services to mobileclients associated with the mobile node.
 18. The mobile node of claim15, further comprising: means for automatically determining whether themobile node has encountered a marker communicated via the roamingmeta-data; and wherein the predetermined criteria is a function of atleast the marker encounter determination.
 19. The mobile node of claim15, wherein the context map is further used to determine when the mobilenode disassociates with a given static access-point of the staticaccess-points.
 20. The mobile node of claim 15, wherein the context mapis further used to determine when the mobile node is enabled toassociate with a given static access-point of the static access-points.